2002 grand prix p0176 obdII code

[natekell]

I have a 2002 pontiac grand prix with a 3.8L and 86000 miles. This car will start and run fine while it is cold but becomes hard starting and will not idle when warm. Also it will die at times when i stop at intersections or if it is in park. the CEL is on and the code that shows is P0176 fuel composition circuit failure. I need to know what i can do about this and where this sensor is located on my vehical.

[BNaylor]

Welcome to AF.

The P0176 generic DTC is not a common issue with the SII 3800 engine and I'm surprised you are getting it. Properly translated it means "Fuel Compensation Sensor Circuit Malfunction". What brand scanner/scan tool is being used?

There are no diagnostics procedures for this DTC in the service manual.

[natekell]

i am using odbII.com on my laptop

[BNaylor]

Something doesn't sound right. You sure the scanner is translating properly? The P0176 should not be triggering because PCM diagnostics does not support it. That respective DTC is not covered in any '97-'03 Grand Prix service manual.

Do the basics like check fuel supply pressure. Just taking an educated guess I would say the it is more like a fuel injection system short or long term fuel trim issue which is in the P0170 DTC range but excluding the P0176 DTC which sounds more like a fluke to me.

[natekell]

i would like to thank you for your input with this issue. last year i was away for awhile and my wife had a "friend" of hers change the fuel filter and i am kind of suspicious that this may be the problem, but as it has hardly been above zero here for the last few weeks i haven't had the desire to crawl under it and inspect the install. as soon as I can I will check that out as well.

[richtazz]

P0176-Fuel Composition Sensor Circuit Malfunction

Bob is correct (of course) that this code doesn't apply to your car. This code only applies to GM flex-fuel vehicles, and GM never produced a flex-fuel Grand Prix. This code applies to a sensor GM installed on flex-fuel cars/trucks, that detects the percentage of ethanol in the fuel so it can compensate fuel delivery when running high ethanol content fuels.

[natekell]

that makes sense as it was what i was finding in other forums. I will try and erase the code and see if it will give me a different code. I suspect that i may have some problem with either the injectors or the fuel pressure at low rpm. What pressure do the injectors typically run at and is there a difference at lower rpm's? If you have any other clue's they would be greatly appreciated.

[BNaylor]

Are you referring to fuel pressure at the front injector rail? Should be at least 48-55 psi at fuel pump prime. Readings will vary at idle or lower rpms and whether vacuum line to the fuel pressure regulator is removed and left on during testing. Just use a standard automotive fuel pressure tester that connects to the Schrader valve by the fuel pressure regulator.